The present invention relates to reagents which are useful in the quantitative determination of proteolytic enzymes. More particularly, the invention relates to peptide derivatives which are substrates for enzymes of the class E.C.3.4.4. These enzymes cleave amide linkages in peptide chains on the carboxyl side of arginine and lysine residues.
Classical substrates for trypsin, thrombin, and related enzymes are amides such as .alpha.-N-benzoyl-DL-arginyl-p-nitroanilide, L-lysyl-p-nitroanilide, .alpha.-N-benzoyl-DL-arginyl-2-naphthylamide and other di, tri and higher order arginine and lysine peptides with chromogenic amide leaving groups [B. F. Erlanger, et al., Arch. Bioch. Biop., 95 (1961)271; A. Riedel and E. Wunsch, Z. Physiol. Chem., 316 (1961)1959; R. E. Plapinger, et al., J. Org. Chem., 30 (1965)1781; L. Svendsen, et al., Thrombosis Res., 1 (1972)267. U.S. Pat. No. 3,884,896]
U.S. Pat. No. 4,070,245 describes compounds of the structure: ##STR2##
U.S. Pat. No. 4,061,625 describes compounds of the structure: EQU Phenylalanyl-prolyl-arginyl-p-nitroaniline
The above prior art compounds are p-nitroanilide derivatives of tripeptides terminating with glycine, phenylalanine or derivatives thereof. The present invention compounds differ from the prior art compounds in that the later are phenoxyacetyl derivatives of dipeptides. These structural differences are illustrated by comparing the structure of phenoxyacetyl-prolyl-arginyl-p-nitroaniline with the prior art compounds.